Amsteel Experts' Advice Needed!

[SteelToe]

Can a large locked brummel splice loop be cut to function as a Y splice? At first glance it seems it should work, and this setup would greatly simplify my suspension (loop on one end, split to Y with a loop on each of those ends).

Would the ability to assymmetrically load the brummel (since it's a Y not a loop) cause it to come loose or slip? While assymetrically loadable, the two lines of the Y will remain roughly alongside eachother (going to each leg) which is why it seems like a loop splice being cut could suffice.

TCB

[Mouseskowitz]

At this point it sounds like you might have to mock up a couple versions to see what you like better. In the end it will probably be more esthetics than function as I doubt you'll get close to the rated strength.

The spice is an idea. A quick search showed that there are 3 ways to do it. A locked brummel like you were taking about, two small lines spliced into a larger one, or eyes you can lock together. These might get you headed in the right direction.
http://www.briontoss.com/spartalk/showthread.php?p=6349
http://www.apsltd.com/c-1539-splicin...heetsguys.aspx

[SteelToe]

Okay, I just finished making a closed-loop for practice, and I want to strangle something with it

I don't know if it's the thicker (1/4" vs 7/64") cord or something, but I takes me at least a half-hour to wrangle each end through the bury with my bent wire "fid". Every demonstration I've seen online shows the cable pulling back through effortlessly by comparison, but I'm fighting it every milimeter. So much that the black Amsteel dye is basically rubbed off on this first one. Is there some trick beyond "scrunching" up the tube to widen it more, or do I just need to look into some other method that passes the tag end through without a bend using a hollow needle (fid)?

I was at first elated by how easy it is to splice this stuff together like Chinese finger traps--now I'm yearning for my Boy Sout days of marlin-spiking Sisal rope together

Thanks a ton for the APS link. A search for "amsteel Y splice" turned up no results or even "brummel Y splice" so I figure I had my terms wrong. It seems like a locked brummel is just as strong whether or not the loop is cut, since the lock will be loaded the same either way. I'll try to do that by lock-splicing in a section of cable (as opposed to actually making/cutting a loop) and see if it's as stable as I'm hoping. Since the two splits would still be close to eachother, the opening in the Amsteel at the brummel penetration shouldn't be spread or stressed too much.

I've attached a crudely drawn sketch of my suspension setup (rotated 90deg on the left side of the sheet);

The sides are attached to a continuous loop passing through the rings as well like many bridge hammocks. A ridgeline passes through descending rings at the ends and bends down to attach to the centerline at the ends of the hammock floor. One end of the ridgeline ends in a whoopie-style adjustable loop splice (it will end up locked once I'm done testing) that larksheads to the head-end of the hammock floor. The other end will have a second leg locked-brummeled on to form a Y, each leg of which will have its own locked eye to attach to the two inseam straps of the hammock floor. The gap between the legs is the entry/exit, and both ends of the legs end within a few inches of eachother (so a loop would work, but would still be loaded like two separate cables).

I hate trying to describe the suspension of this design since it's a bit difficult to understand without a finished model to point at (which I obviously don't have yet ). I'll try to have some pics of what I'm going for by the end of the day, and with any luck I'll be able to sit in the unfinished sling by the end of the weekend.

TCB

[Mouseskowitz]

I think "Y rope splice" is what I searched for. Larger diameter stuff is supposed to be easier from what I hear. Did you do your taper before pulling it through the bury? That seems to make it easier from what I remember but it's probably been a year since I've done any rope work.

I was doing some more looking around and found this. There is some destructive testing of Y splices mentioned as well as a ton other stuff. It also has info on knots in amsteel, the first that I've seen.

[SteelToe]

Wow, I had no idea a whoopie sling was about as strong as an eye-splice (though I guess it makes sense because the principles are the same). That's a cool paper, and really makes it clear that knots are bad news in Amsteel . I only wish that they'd tested a true locked-brummel, because I'm curious if it might actually be weaker than a simpled bury because more of the load is concentrated at the lock. I wonder if it may be wiser to do simple buried loops and then lock-stitch them to keep them from moving.

I figured out what I was doing wrong with my splicing; I had tapered the ends of the cable properly, but I was putting the full-thickness section through the eye of my pull-wire, and the doubled-up full width of the cable is too much to fit through the center easily. By putting just the very tip of the tapered area at the bend, the folded width is narrow enough to slide through much, much easier. I had been worried that the loose fibers from tapering would unravel if they weren't all behind the bend, but it seems like that's a non issue.

Now that the construction issue's been resolved, things should start moving much more quickly

TCB

[Mouseskowitz]

There's a wide range of figures on the strength of whoopies. Samson's official figure is 60% although they told someone on the forum that in reality it's more like 80%, so similar to this paper's data. One of the cottage industry guys did some testing and put the number in the 95%+ range.

If you've never looked at it, Samson has good splicing instructions on their site. For Amsteel you want to look at the 12-strand Class II stuff. They tend to list the strength of the particular splice at the top of the first page.

Gland you figured out how not to fight the bury. If you're at all worried about things coming apart in the taper while you're pulling it, a wrap of masking tape will keep everything together.

[SteelToe]

So, it seems an issue I was mildly dreading has, in fact, appeared. Luckily it looks like I (might) have two avenues of attack.

I have nearly all of the main supports of the sling put together, and now I'm fine tuning the lay (you have no idea how awesome it is to hang and not be squeezed by anything--it's like floating ). As most of ya'll know, it's more comfortable if our center of mass doesn't sit at the very bottom of the hammock. Because my current ridgeline attaches to each end of the hammock after passing through descending rings at each end (the "fixed support") the floor of the hammock tries to balance the tension at each end by slouching my CM right into the middle of the lay, causing my feet to raise up and the blood to rush to my head (only slightly, but it's still uncomfortable after 15min or so).

The two solutions I have devised are:
1) A knot or hitch of some sort at the rings will keep the Amsteel from sliding through. Amsteel is slippery and doesn't like knots, so I don't like this idea, but perhaps there is a climbing knot or something I'm not familiar with that might work. I would try to simply stitch the Amsteel together to form an "eye" but the 30deg angle of the cables precludes that. I'd prefer not to cut the cord and form two eye-splices since that can't easily be undone, but that's my fallback. It's also overkill since there isn't much force required to keep my imbalance in check (20lbs at most)

2) I've finished tweaking the postion of the calf supports (really difficult to nail down, btw), so the next step is to attach the vertical "door panels". Because they extend from the ridgeline above to the other end of the cable below at the inseam, I think I could tension it in a way to provide the necessary counter-balancing force in the cable. Only problem with this is that it's harder to estimate what I'd need with this setup, so a lot of guess-check-rip-redo would be needed. The panels are labeled "G" in the side view of my concept sketch.



TCB

[Mouseskowitz]

Knots in Amsteel = very bad. I don't know if you looked at the section in that paper on knots. Page 22 of the pdf.
If I understand the problem correctly your hammock is sliding on the Amsteel ridge line changing the horizontal angle of you lie. So, a solution is needed to affix the Amsteel to the ring.
Based on that thinking here is my thought. Add your other panels as it sounds like that might change things some. Then to attach the ridge line to the ring either larks head or make an eye on the ring. Take the tail of the eye and bury it in the ridge line. The finger trap concept should hold it enough for you to tweak it by playing with the exact amount buried. Once you've found the sweet spot lock stitch it in place.
That may be over engineering the problem, if I'm understanding it correctly, but it would seem somewhat fitting for your fancy rig.